I've had an opportunity recently to purchase a Piper PA28-140- absolute
creme puff cosmetically... but the problem (and reason for the good
cosmetic condition) is that the plane has been sitting in an
enironmentally stable (dry, 50-80 degree ambient temperature) for
almost a decade now.

(For those who responded to my other post, I know this is a huge step
down from what I was looking for, but It would just serve as a
timebuilding local puddlejumper/toy for a few years until I can afford
something better, and at the price, I'm garanteed not to loose anything
on depreciation)

The purchase is for a _very_ good price.

Before she went into the hanger, the ship had 300 hours on a rebuilt
engine (2300 hours TTAF).

I'm getting wildly varying advice from shops. The one shop whose
actually seen her has been assuring me that considering the condition
of storage and the good condition before she went in, He's reasonably
sure (and he's going to confirm/deny with a prepurchase this week) that
all she'll need is to have all of her seals replaced, as well as a good
prelubrication job done. He said that as long as I go through and make
sure that the engine is well lubricated and sealed before I turn it
over even once, then there really shouldn't be any damage worthy of a
rebuild.

The other shop, the one who I have more experience and tend to trust
more (although they tend to be very by-the-book and high-end) has
_adamantly_ insisted that If I get the plane, she will need a full
engine rebuild. They said that even if she hadn't been static for 10
years, Lycoming insists that all O320's be rebuilt at 2000 hours OR 10
years.

Both shops agree about the rest of the necessary work (Avionics, new
struts, new tires, new seatbelts, etc). The only place they disagree
is the engine.

I'm not sure what to think... On one hand I agree, err on the side of
safety. On the other hand, everything I know about engines suggests
that as long as A- there was no opportunity for the introduction of
moisture and B- the engine is fully lubricated/sealed before running,
engine corrosion/wear shouldn't be an issue.

I'd love to hear some of your takes on the situation.